Neutralizer composition



Patented Nov. 16, 1943 srrss earner 2,334,255 NEUTRALIZER. coivmosrrron No Drawing. Application December 18, rate, Serial No. 370,737. In Australia August 2, 1939 6 Claims.

This invention relates to the neutralization of noxious gases that are liberated upon the firing of explosives such as are used in carrying out mining and such like operations in which the explosive action is accompanied by the evolution of oxides of nitrogen, carbon dioxide and, in some cases, hydrogen sulphide, sulphur dioxide and the like, according to the explosive used and the material being blasted. The invention is particularly applicable for use in connection with underground blasting operations or in similar situations where there is insufficient ventilation, air movement or atmospheric air to effectually and rapidly dissipate the noxious gases liberated by the blasting.

It is well known that the gases arising from the use of explosive in mining operations are harmiul or irritating to the human system, andone of the objects of the present invention is to provide a simple, inexpensive and practical method whereby such noxious gases may be neutralized in a most speedy manner, thus protecting the miners or'other operatives and minimizing the delay that usually occurs logaween' the firing of the explosive and the time by which the noxious gases have been rendered innocuous to an extent that is sufiicient to permit the operatives to return with safety to the site of the explosion},

In accordance with the invention the method consists in generating ammonia adjacent to or in the immediate vicinity of the explosive, simultaneously with the explosion, by utilizing the heat of the explosion to initiate reaction in a mixture containing magnesium oxide and a substance capable of reacting with magnesium oxide under the influence of heat and dissociating so as to generate ammonia, the mixture being placed in juxtaposition to the explosive prior to the explosion.

For this purpose, the invention provides a composition containing magnesium oxide and a substance, such for example, as ammonium chloride or sulphate, which is capable, by reaction with the magnesium oxide under the influence of heat, of dissociating and generating ammonia. The composition is placed in juxtaposition to the explosive i. e., in the usual drill holes that are formed in the rock or ore to be blasted, so that upon the firing of the explosive ammonia will be generated at, and immediately succeeding the moment of explosion, in suflicient quantity as to neutralize substantially all, or at least a considerable proportion, oi the noxious gases that are liberated by the explosion.

In order to facilitate commercial distribution and use of the composition it is preferably made into the form of blocks, pellets, tablets or the like of a convenient size and shape and for this purpose the ingredients, while in a granular or powder condition, are suitably mixed together, if necessary with a suitable binding agent such as a mucilage, and the mixture is then compressed under a degree of pressure that issuflicient to ensure that the resulting blocks or tablets will maintain their shape until used.

The use of magnesium oxide as an ingredient of the composition is of considerable importance in that it renders the composition substantially immune from evolution of ammonia due to atmospheric moisture. We are aware that for similar purposes it has been proposed to utilize cardboard, cartridges or cylinders divided by a transverse partition into two compartments, one of which ischarged with an alkaline salt such as sal-ammoniac, and the other charged with the oxide of an alkaline earth, as for example, calcium oxide, but with such and other proposals it is essential, for practical purposes, to take special precautions against the effects of moisture. Thus, in addition to the ingredientsbeing separated from each other and enclosed in a cardboard or like container, the container has to be rendered damp-proof as by being greased, and also should preferably be enclosed in a water-proof sleeve, the ends of which are'approximately tied or secured.

According to a preferred form. of the invention the composition contains ammonium chlo ride and finely divided magnesium oxide which may be in molecular proportions, although it is usually found desirable to have a slight excess of magnesium oxide. The composition may be conveniently formed into tablets or the like of about 25 to 28 grams in weight. If so desired the composition in its powder condition may be charged into relatively small tubes composed of paper or like material but'as this would add to the production costs without producing any commensurate emciency, it is generally more suitable to use the composition in tablet or like form as before referred to.

According to the practical example of carrying the invention into effect, twenty-four (24) of the compressed tablets each weighing from 25 to 28 grams were used in association with forty-seven (47) lbs. of an ammonium nitrate explosive and two hundred and ten (210) feet of fuse, the tablets being placed in a charged drill hole adjacent to the primer and being broken up into a somewhat powdered condition to include in the manganese dioxide has by the usual ramming operation. It was found that the atmospheric air in the vicinity of the explosion was substantially free from nitrous oxide within about twenty minutes after the explomon.

' It would appear that upon the explosion occurring, ammonia is liberated due to the heat of the explosion initiating a reaction between the ammonium chloride and the magnesium oxide in accordance with the following equation:

-The ammonia so liberated would seem to act as a neutralizing agent whilst state, so that its neutralizing properties are availedr'of to the best 'eii'ect. Thus the ammonia reacts with the noxious acidic gases, more partic ularly the oxides of nitrogen gases given oil by the it is in the nascentexplosive, whilst the magnesium radicle reacts with the acid radicle of the ammonium salt. Any sulphur trioxide that may be present will prererentially react with a proportion of the magne-- sium oxide and form magnesium sulphate.

When carrying out ing, for example a high sulphide content, and which thereby develop hydrogen sulphide upon fracture by explosion, an appropriate amount of zinc oxide may be included in the composition in order to absorb the hydrogen sulphide. It is not feasible to predetermine the proportion of It will be appreciated that on account of the many variable and incalculable factors involved, such as burden," weight of explosives allowed per ton of rock, presence or absence of moisture, strength of detonators and so on, it is impracticable to lay down any specific proportionate quantities of the ingredients or the total amount operations upon ores havammonium sulphateof the composition that should be used. Generally speaking, it will suffice to place one or more of the tablets into each drill hole. Any excess ammonia that may be generated will be harmless and in any event its presence will indicate that sumcient time has elapsed since firing as to enable the site of explosion to be approached with safety.

Whilst according to the example of the invention before indicated, it is advantageous to utilize ammonium chloride as the source of ammonia, it is to be understood that ammonium sulphate may be employed with equal efiectiveness.

Having now described our invention what we claim as new and desireto secure by letters Patent is:

1 A composition of matter for neutralising noxious gases liberated upon the firing of explosives in mining and like operations. comprising a mixture containing magnesium oxide and an chloride and ammonium 2. A composition of noxious gases liberated sulphate. matter for neu upon the firing of explo- 'sives in mining and like operations, comprising a mixture containing magnesium oxide and ammonium chloride in substantially molecular proportions. I 3. A composition of matter for neutralizing noxious gases liberated upon-the firing of exposives in mining and like operations, comprising a mixture containing magnesium oxide and in substantially molecular 4. A composition 7 according to claim 1 containing also zinc oxide.

5. A composition according to claim 1 containing also manganese dioxide.

6. As a newcomposition of matter. a moulded pellet or the like composed of a nesium oxide and an ammonium salt lclected from the group consisting of ride and ammonium sulphate, like being stable against evolution of ammonia in moist'atmosphere and generating ammonia proportions.

under conditions of intense heat.

HARRmdJHARL'roN DOD. JOHN BROOK LEWIS.

mixture of mag-- 

